A genetic study of Scott and Mark Kelly, most famous as the twins who both became astronauts, has found that long-duration space flight may cause changes in the way that genetics are expressed. Scott Kelly spent 340 days on the International Space Station while his brother stayed on Earth as a control to study the effects that long-duration space flight has on the human body.
During that time, telomeres that serve as a protective cap at the end of each of Scott Kelly’s chromosomes increased their length while he was on the space station. The levels of chemical markers in the mythel group, which affects DNA expression, also decreased in Scott Kelly but increased in Mark Kelly during the same time period. The levels of both have since returned to normal.
Other Factors May Be Involved
The study has not yet been peer-reviewed and some of the changes may be the result of changes other than being in a microgravity environment, such as alterations in diet and sleep habits. The results have prompted researchers to express interest in conducting further research to see if future International Space Station crew members display similar changes. They also have a considerable amount of data from the genetic studies remaining for continued study.
One thing that researchers might look into is what might have caused Scott Kelly’s telomeres to increase in length. The shortening of telomeres could be prevented by increased production of an enzyme called telomerase. Too much of this enzyme contributes to cancers by disrupting the balance between cellular replication and cellular death. Does this mean that Scott Kelly was at greater risk of developing cancer during his 340 days in space? Possibly, but his telomeres did return to normal once he returned to Earth.
Interesting Implications For Longevity In Space
Telomeres are designed to protect the ends of chromosomes from damage, especially during the cellular replication process. When chromosomes are “snipped” as a normal part of he process, they are normally snipped at the telomeres. This causes telomeres to become shorter over time, which poses an increasing risk of chromosomal damage as a person ages and telomeres stand a chance of becoming excessively short.
That makes it more interesting that Scott Kelly’s telomeres seemed to increase in size during his 340 days in outer space. Shortened telomeres are considered a normal part of the aging process and may cause cells to stop replicating past a certain point and enter a phase known as cell senescence. Essentially, the cell goes into decline in the cellular version of the aging process.
It is possible that extended space missions, such as missions to Mars, could slow down cellular aging by increasing the length of telomeres. Would it be enough to combat the effects of radiation and other hazards that might cause premature aging and cancers? Scientists such as Susan Bailey, a radiation biologist at Colorado State University in Fort Collins, who is assisting with the study, thought that it warranted a closer look.
“That is exactly the opposite of what we thought,” she told reporters.
Scientists plan to recruit ten unrelated astronauts to study this phenomenon more closely. This separate study is expected to be completed in 2018.